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1 Dorsal fins are found on the back of the fish. 2  There may be up to three of them. 3  The fish uses this fin for balance in the water and sudden movements. 4  Caudal fins are also known as tail fins.5  This is what we refer to as the fish's tail. 6  Anal fins are on the ventral (bottom) surface of the fish, behind the anus. Dorsal fins are found on the back of the fish. 2  There may be up to three of them. 3  The fish uses this fin for balance in the water and sudden movements. 4  Caudal fins are also known as tail fins.
A fish can have up to three dorsal fins. The dorsal fins serve to protect the fish against rolling, and assist it in sudden turns and stops. 1  In anglerfish, the anterior of the dorsal fin is modified into an illicium and esca, a biological equivalent to a fishing rod and lure.he pelvic fin assists the fish in going up or down through the water, turning sharply, and stopping quickly. 1  In gobies, the pelvic fins are often fused into a single sucker disk. 2  Pelvic fins can take many positions along the ventral surface of the fish.